An underwater test-fire of strategic submarine ballistic missile is pictured in this undated photo released by North Korea’s Korean Central News Agency

North Korea launched what appeared to be a second intermediate-range Musudan missile on Wednesday that flew about 400 km (250 miles), in what appeared to be its most effective test yet, hours after another launch failed, South Korea’s military said.

It was not immediately clear if the second Musudan launch, about two hours after the first, was considered a success or failure, or how the flight ended. However, the distance it covered was theoretically more than halfway towards the southwest coast of Japan’s main Honshu island.

The missile reached an altitude of 1,000 km (620 miles), indicating North Korea had made progress in its missile programmes, Japan’s Minister of Defence Gen Nakatani said.

The first missile was launched from the east coast city of Wonsan, a South Korean official said, the same area where previous tests of intermediate-range missiles were conducted, possibly using mobile launchers.

South Korea’s Yonhap news agency, quoting a government official, said it disintegrated mid-air after a flight of about 150 km (95 miles).

The launches were in continued defiance of international warnings and a series of U.N. Security Council resolutions that ban the North from using ballistic missile technology, which Pyongyang rejects as an infringement of its sovereignty.

Wednesday’s first launch would have been the fifth straight unsuccessful attempt in the past two months to launch a missile that is designed to fly more than 3,000 km (1,800 miles) and could theoretically reach any part of Japan and the U.S. territory of Guam.

Jeffrey Lewis of the California-based Middlebury Institute of International Studies said missiles are usually fired at a certain angle to maximise range, so the high altitude of the second launch may have been chosen deliberately to avoid Japanese airspace.

“That suggests the missile worked perfectly,” Lewis said. “Had it been fired at its normal angle, it would have flown to its full range.”

Lewis said failures were a normal part of testing and that North Korea would fix problems with the Musudan sooner or later.

“If North Korea continues testing, eventually its missileers will use the same technology in a missile that can threaten the United States,” Lewis told Reuters.

SERIOUS PROVOCATION

Nakatani said North Korea’s repeated missile launches were a “serious provocation” and could not be tolerated.

Japan indicated after the first launch that it would protest strongly because it violated a United Nations resolution, even though the launches posed no immediate threat to Japanese security.

In Seoul, South Korea’s presidential office said a national security meeting would be convened later on Wednesday to discuss the latest missile launches.

The U.S. military detected the two missiles, most likely Musudan, from North Korea, the U.S. military’s Pacific Command said. A Pentagon spokesman said both missiles fell into the Sea of Japan.

Yonhap, citing an unidentified government source, said on Tuesday the North had been seen moving an intermediate-range missile to its east coast. Japan put its military on alert in response.

North Korea is believed to have up to 30 Musudan missiles, according to South Korean media, which officials said were first deployed around 2007, although the North had never attempted to test-fire them until April.

The U.N. Security Council, backed by the North’s main diplomatic ally, China, imposed tough new sanctions in March after the isolated state conducted its fourth nuclear test in January and launched a long-range rocket that put an object into space orbit.

North Korea has conducted a series of tests since then that it claimed showed progress in nuclear weapons and long-range ballistic missile capabilities, including new rocket engines and simulated atmospheric re-entry.

The two Koreas technically remain in a state of war after the 1950-53 Korean War ended in an armistice, not a peace treaty.

A spokesman for South Korea’s Unification Ministry said North Korea should channel its efforts into the welfare of its people and peace on the Korean peninsula rather than developing its missile technology.